Investigation of egg weight and gremlin2 mRNA expression in ovarian follicles of Boschveld Chicken breed

Abstract

Ovarian follicular development, a key factor affecting egg production, is controlled by a complex network of genes, growth factors, and signalling pathways. Egg weight is a key economic trait in poultry, directly affecting market value and consumer choice. This study aimed to examine the correlation between egg weight and egg quality traits, as well as gremlin2 (GREM2) gene mRNA expression levels in the preovulatory follicles of the Boschveld chicken breed. The study was conducted at the University of Limpopo experimental farm. Six animals were used in this study, and 300 eggs were collected from 50 Boschveld chickens. A completely randomized design was employed. Pearson’s correlation analysis revealed that egg weight was significantly (P < 0.01) and positively correlated with yolk weight, shell weight, albumen weight, egg length, egg width, shell surface area, and egg volume, while it was negatively correlated with shell ratio. Real-time PCR showed significant (P < 0.05) differences in GREM2 mRNA levels across preovulatory follicles, with F2 follicles showing the highest expression and F6 the lowest. These results imply that egg weight is a reliable indicator of both internal and external egg quality traits in Boschveld chickens and that GREM2 expression affects follicular development and ovulation hierarchy. The findings of this study provide valuable insights for future breeding and selection strategies aimed at enhancing egg production and reproductive efficiency in indigenous chicken populations.